Now although I have a Nikon camera at the moment I have no lenses with an aperture ring and I plan to start with just a 50mm lens so I'm not tied at all to the F mount and am looking at alternatives.
I want something with aperture priority and manual mode but don't really care for timers etc.
I've heard good things about the Olympus OM-10 and I like the look of it even though it's only aperture priority without the adapter. I don't really want anything too modern as I like the look of these old cameras.
There are a lot of options, and I'm sure you'll hear a lot of opinions on the matter. My own: First, I'm not too familiar with the Olympus line, but AFAIK it's no longer in production, and although it was popular it was never top-sales popular, so lenses might be harder to find than for some other brands. My impression (just that; I've not studied the statistics) is that the most popular lens mounts/brands are M42 screw mount, Pentax K-mount, Minolta, Nikon, and perhaps Canon. I'm not too familiar with the details of the last three lines; there may be differences between specific mounts for each that are important.
M42 screw mount is a very old design that was used by many manufacturers, but there's little new production today. These lenses are less convenient to use than bayonet-mount lenses, since they take longer to change, and few M42 cameras have any form of automatic exposure. (I can't think of any off the top of my head, in fact.) There are two main variants: manual and automatic. The former type adjusts the aperture as you move the aperture ring. The latter adds a pin so that the aperture ring doesn't immediately stop down the aperture; the pin enables the camera to stop down the lens when you release the shutter. Automatic cameras can use manual lenses but not vice-versa. Some lenses have "A/M" switches so they can work either way.
Pentax K-mount was used by Pentax and several less popular makes (Ricoh, Vivitar, Chinon, Cosina, etc.). Between them, and with the fact that the Pentax K1000 became a very popular student camera, there are lots of K-mount cameras and lenses on the market, and they're still being made new. There are a handful of variations of the K mount to add features such as camera control of aperture (for shutter-priority auto exposure and full-program exposure) and auto-focus. These features are mostly backward-compatible with older versions of the K-mount. I seem to recall hearing of some caveats in this regard, but I don't recall the details. (I stay away from autofocus, myself, so the basic K mount and variants to support auto exposure are plenty for me.)
I agree with filmamigo that the K1000 is overpriced. It's also an all-manual camera, so it doesn't satisfy your requirement of having aperture-priority automatic exposure. Among cameras I own, the Chinon CE-4s, Pentax P30t, and Ricoh XR-X 3PF might meet your needs. The Chinon and Pentax are pretty similar overall, although the Chinon uses manual film speed setting whereas the Pentax uses DX codes (with no override possibility, which is a big minus if you bulk-roll your film or like to shoot at anything other than box speed). The Ricoh has a power winder and a wider range of exposure options (including aperture-priority, shutter-priority, and full-auto, although the last two only work with compatible lenses, which are fairly rare). Of these, I'd say the Chinon is probably my favorite -- or would be except that mine has a few sample-specific quirks. The Ricoh is certainly my most flexible camera, but that flexibility comes at the cost of confusing controls that are sluggish to use for certain things. (It takes about five seconds to switch from manual to automatic exposure mode, for instance.) Of course, these comments are specific to the particular models I've got; there are Pentaxes and Chinons with power windows and Ricohs without them, for instance.
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